Microsoft Word tutorial origin doc

s
x
x
Exp
s
k
f
Av
π
(2a) 
in which f is the frequency of occurrence, k is a constant, s is the standard deviation, x represents 
individual values of the mass and x
Av
is the average value of the masses. Assigning P1 = k, P2 = s and 
P3 = x
Av
. The equation in Origin syntax can be written as
)
2
))^
2
*
2
/(
)
3
((
(
*
))
5
.
0
)^
*
2
(
*
2
/(
1
(
P
P
x
Exp
pi
P
P
−
−
(2b) 
This is the model we shall fit to the data in Columns F and G in Table 1.
B. Plotting the data 

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1
0
0 
Open the FORMATTED TEMPLATE file prepared in Part II-K. Bring in a new worksheet (Part II-K) 
and enter data from columns F and G of Table 1 into Columns A and B of the Origin worksheet. Highlight 
Column B, bring the formatted graph to the forefront and Click “Graph/Add plot to layer/Scatter/OK”. A 
peak-shaped plot should appear. 
C. Fitting a model to the data 
The following is an abbreviated version of the procedure described in more detail in Part III-C. 
1. With the plotted curve in the forefront, Click “Analysis/Nonlinear curve fit”. 
2. Click 
“New” and set the “Number of parameters” to 3. 
3. Type Eq. 2b above into the “Definition” box; DO NOT INCLUDE AN = SIGN.
4. Click 
“Accept”. 
5. Click “Select data set/B/Assign/Start fitting”. 
6. Set P1 to 0.05 and P2 to 0.001, P3 = 0.46 and Click “1 iter”.
7. If there is no error message, Click “10 Iter” several times until values of the fitting parameters do not 
change.
8. If there is an error message, Click “OK” and check initial estimates of parameters. If initial estimates 
are as suggested above then Click “Select function”/Edit” and look for errors in the equation entered 
into the Definition box. Then follow steps 4 – 7 above. 
9. Successful completion should give a fitted bell-shaped plot through the data. 
10. Label the abscissa (Mass(g)) and ordinate (Number) and save and print the figure.
11. Compare best-fit values of P3 and P2 to the calculated average (0.4649 g) and standard deviation 
(0.00116 g).
VI. NONLINEAR DATA SET (TRANSMITANCE)
Data for percent transmittance vs. concentration (Columns A and C) will be used to illustrate 
application of the curve-fitting process to a nonlinear data set. 
Based on the following relationships among absorbance, A, concentration, C, and percent 
transmittance, T (%), 
A
a bC
T
= +
= − log
(%)
100
(3a) 
it follows that percent transmittance is related to concentration as follows 
T (%)
= 100 x 10
-(a +bC)
(3b) 
Use the following steps to illustrate the use of Origin software to fit this nonlinear relationship. 
1. Close the current Origin file and open FORMATTED TEMPLATE. 
2. Bring in a new worksheet (Part II-K). Enter data from columns A and C of Table 1 into Columns A 
and B of the Origin worksheet. Highlight Column B, bring the formatted graph to the forefront and Click 
“Graph/Add plot to layer/Scatter/OK”. A scatter plot of Transmittance vs. Concentration should appear. 
(Transmittance should decrease nonlinearly with concentration.) 
3. Add values in Column E of Table 1 as error bars (Section II B). 
4. Use procedures described in Part V to fit the two-parameter model in Eq. 3b to the plot of percent 
transmittance vs. concentration. (You can use either the Origin-defined parameter names (P1 and P2) or 
check the “User defined parameter names” box and use a and b (or any other symbols you choose) as 
the parameter names. 
NOTES: 1. The expression in the “Equation box” should be 100*10^(-(
α+βX)) if you use user-defined 
symbols, 
α and β, or 100*10^(-(P1+P2*X)) if you use Origin-generated symbols, P1 and P2, for fitting 
parameters. 

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1 
2. Use values close to the intercept (a 
≅ 0.02) and slope (b = ≅ 1.2) values obtained from the linear fit 
of absorbance vs. concentration as initial estimates of the fitting parameters. (For some unknown reason, 
the version of Origin used to write this tutorial does not like “0” as an initial estimate.) 
3. Best-fit values of a and b are not expected to be exactly the same for the linear and nonlinear fits 
because these are experimental rather than ideal data. 
5. Use Eq. 3b, a spread-sheet program and computed values of parameters, a and b or P1 and P2, to 
compute values of transmittance for values of concentration between 0 and 2.75 with a step size of 0.025 
i.e. T (%)
n
for C
n
= 0.000, 0.025, 0.050, 0.075 .... 2.70, 2.725, 2.750 (x 10
-4
mol/L). (NOTE: Because the x 
10
-4
mol/L unit is not included in the Origin worksheet, do not include it in the spreadsheet calculations. 
These calculations are done most easily using a spreadsheet and data can be transferred from the 
spreadsheet to an Origin file using the “Copy”/”Paste” operations. With Microsoft EXCEL, the “Edit”/“Fill” 
(pull-down menu) can be used to generate the series of concentration values. Ask for help if you need it. 
6. Construct a formatted graph (Part IV-B) containing plots of computed and experimental data for 
Transmittance (%) vs. Concentration (10
-4
mol/L). For the concentration range from zero to 2.75 x 10
-4
mol/L. (Use a dashed-line for computed values and an open-triangle scatter plot for experimental data 
and remember that the line should not overlay the experimental points (Part IV-B).) 
VII. USING “HELP” 
Origin includes an excellent “Help” section; you should learn to use it. For example, to get 
information about adding error bars to a graph: 
1. Click on “Help/Search” and type “error” in the dialog box. 
2. Select “Error bars dialog box/Display”. 
3. Click on the double arrows right, “>>” until you find “Adding Error Bars using the Select 
Columns for Plotting Dialog Box” which gives the procedure summarized in the tutorial. 
You will probably need to use “Help/Layer” to learn how to use the “Layer n” dialog box.
ACKNOWLEDGEMENT: I thank Mr. Henry Gaw, a former Purdue student, for the generous gift of funds 
with which to purchase the Microcal Origin software. 
H. Pardue, 1/02 

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1
2
2 
This figure was generated using a FORMATTED TEMPLATE as described in Parts II-J and IV-B. 
COMPUTER: HOME, FOLDER:CHEM 321/323_FALL_OO, SUBFOLDER: SPECIAL TOPICS, FILE: 
ORIGIN TUTORIAL_F00 
REPORT 
No narrative report is required. You should print and turn in four figures, Figures to be turned in are 
those associated with: 
Part 
II-J 
Part 
III-B-3-f 
Part 
IV-B-3-e 
Part 
V-C-10 
0.0
0.5
1.0
1.5
2.0
2.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Line
A = 0.02 + 1.2 C(10
-4
mol/L)
Experimental and fitted values of absorbance vs. 
concentrationfor the spectrophotometric 
determination of Fe(II).
Abs
or
banc
e
Concentration (10
-4
mol/L)